Abstract
This study documents the projected changes in several components (precipitation, runoff, snow cover and depth, soil moisture) of the hydrological cycle in Central-Western Argentina (CWA) based on the simulations from the IPSL-CM6A-LR model for the warming levels proposed in the Paris Agreement. These warming levels represent the future increase in mean annual temperature of 1.5 and 2°C compared to pre-industrial conditions. A novel regional approach, that uses a set of low-emissions shared socioeconomic pathways (SSP) compatible with the Paris Agreement goals, has been applied here for the evaluation of the potential impacts of temperature increase in both the mountainous areas of the Andes and the lowlands on the eastern portion of CWA. Our results show that the timing of reaching the 1.5°C warming level would be between 2032 and 2036 in the CWA lowlands east of the Andes, while this warming level in the Andes mountains of CWA would be 10–15 years earlier as result of the stronger warming with elevation. The higher 2°C warming level would be reached before 2050 in the Andes mountains. Even using the more aggressive mitigation pathways available in the scientific literature (SSP1-1.9 and SSP1-2.6), the IPSL-CM6A-LR model ensemble shows a robust drying signal in the wintertime precipitation over the Andes mountains, which is a concerning result because it implies a reduction of the already scarce water resources draining to the adjacent semi-arid foothills. Our results also show that this drying should be linked to the poleward expansion of the Hadley Circulation. In the lowlands farther east from the Andes, the summertime monsoonal precipitation provides the water resources that are projected to increase under the selected emissions pathways. The expected changes in the analyzed components of the hydrological cycle would be strengthened under the 2°C warming level, particularly the decline of snow amount and surface runoff in the Andes. The results of this study provide insights into the expected impacts of the 1.5 and 2°C warming levels in the CWA regional water resources, which may set the stage for the new discussions of possible options to mitigate them at country and regional levels.
Highlights
Global warming is expected to cause widespread changes to the terrestrial water cycle, as a result of variations in largescale circulation patterns
We performed a comparison between the reference datasets (CRU TS 4.04 and ERA5-Land) and the Institut Pierre-Simon Laplace (IPSL)-CM6ALR model outputs, considering the most relevant variables
The simulated precipitation by the IPSL-CM6A-LR model agrees better with ERA5-Land than with Climatic Research Unit (CRU) TS 4.04 dataset in both sub-domains, which might be linked to the limited amount of observations over Central-Western Argentina (CWA) that are used as input for the CRU TS 4.04 database (Rivera and Arnould, 2020)
Summary
Global warming is expected to cause widespread changes to the terrestrial water cycle, as a result of variations in largescale circulation patterns. In particular for the arid to semi-arid regions of the world, the water availability for cities, energy production and agriculture, among other activities, is facing more recurrent reductions (Cai et al, 2012; Herrera-Pantoja and Hiscock, 2015; Donnelly et al, 2017). This is the case of Central-Western Argentina (CWA), a dry region where the interplay between the complex topography and the atmospheric circulation determines a wide range of hydroclimatic features (Camisay et al, 2020). Winter snow accumulation along the Andes plays a major role in the water availability during summer months, with crucial relevance for agriculture (Viale et al, 2018)
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